Shane Oldfield, a pilot for the Utah Highway Patrol, speaks Friday about the search for and rescue of lost hiker William Martin LaFever, 28, of Colorado Springs, Colo., in Salt Lake City. The father of the autistic man who barely survived three weeks in remote southern Utah said his son was an experienced mountaineer but was out of his element in the harsh desert. (ASSOCIATED PRESS / The Deseret News, Scott G. Winterton)

SALT LAKE CITY (AP) — The father of a 28-year-old autistic man who barely survived three weeks in remote southern Utah says his son was an experienced mountaineer but was out of his element in the harsh desert.

John LaFever said Friday that his son William made one crucial mistake: setting off for a 150-mile journey along the wild Escalante River without food or equipment that was apparently stolen before his trip got under way.

Authorities say William LaFever, of Colorado Springs, Colo., apparently didn’t realize the distance involved with his plan to hike from Boulder, Utah, to Page, Ariz.

William LaFever is being treated for starvation and dehydration at Dixie Regional Medical Center in St. George, his father said.

“He started out this journey with everything he needed to survive — but it got stolen from him,” John LaFever said. “He thought he could do this on his own without any supplies or equipment, which was a bad decision.”

The man has spent a lot of time backpacking in the Colorado mountains and “never had any problems at all,” John LaFever said. Utah’s twisting, arid canyons turned out to be “totally different.”

He traveled about 50 miles over at least three weeks before he was found Thursday by a Utah Highway Patrol helicopter.

“He was in the right spot when the helicopter flew overhead. If he was under a tree they wouldn’t have seen him,” John LaFever said. “He wasn’t able to walk, he was so weak. He was barely able to get an arm up to wave to the helicopter. When they landed, he just wanted to talk to somebody. He’s going to recover from this.”

William LaFever’s mother, Anita Jennings of Colorado Springs, said Friday she was still “kind of in shock.”

“I’m just so thankful they found him,” she said.

Jennings said her son believes he is an American Indian and recently gave up his Colorado Springs apartment and sold many of his possessions to go to the Utah desert.

She said his family tried to dissuade him but couldn’t.

“He’s just a little stubborn. There’s nothing you can do. He’s very strong-willed,” she said.

Utah Highway Patrol pilot Shane Oldfield said when he spotted LaFever, the man was lying in the river wearing only his underwear.

Oldfield said LaFever was severely emaciated, estimating the 6-foot-tall man weighed less than 100 pounds when they found him.

Oldfield described LaFever as “borderline belligerent” because he initially refused to get in the helicopter.

“He wanted at least 15 to 20 minutes to just sit there and we wanted to get him to the hospital,” Oldfield said.

They compromised, giving him about eight minutes to eat a granola bar and drink some Gatorade before taking flight.

“He knew he needed to be rescued, but he wasn’t in any hurry,” Oldfield said. “He hadn’t seen anybody in a long time.”

Oldfield said LaFever was talkative, and recalled eating a frog a day earlier.

“That didn’t sit too well in his stomach so he didn’t want to do that again,” Oldfield said.

The pilot said he believes LaFever’s mental condition allowed him to look at the situation different than an average person.

“It was a spiritual experience for him,” Oldfield said. “He viewed it as a positive, life-changing event. He felt the desert was calling him. That’s why he went on the trip in the first place.

“I think he’s lucky to be alive,” the pilot added.

The hiker survived on frogs, roots and water from the river in “some of the most rugged, unforgiving terrain you will find anywhere on Earth — jagged cliffs, stone ledges, sandstone, sagebrush, juniper,” Garfield County sheriff’s spokeswoman Becki Bronson said.

Deputy Ray Gardner, who had recently completed training in search and rescue operations for people with autism and was aboard the helicopter, said LaFever would not have survived another 24 hours. He learned in his training that people with autism are typically attracted to water, so they flew along the river during their search.

LaFever was trying to get to Page because his father told him he would wire money to him in there, the sheriff’s department said.

William LaFever had called his father on June 6 or 7 to say he was hiking in the Boulder area with his dog, and that someone had stolen some of his hiking gear and he had run out of money. John LaFever told his son to catch a ride to Page to collect the money.

Unbeknownst to his father, William LaFever apparently decided to hike down the Escalante River and then hitch a boat ride along Lake Powell to Page, rather than try to catch a ride, the sheriff’s department said.